Method and system for displaying stereoscopic detail-in-context presentations

ABSTRACT

A method for generating a stereoscopic presentation of a region-of-interest in a monoscopic information representation. The method includes the steps of: (a) selecting first and second viewpoints for the region-of-interest; (b) creating a lens surface having a predetermined lens surface shape for the region-of-interest, the lens surface having a plurality of polygonal surfaces constructed from a plurality of points sampled from the lens surface shape; (c) creating first and second transformed presentations by overlaying the representation on the lens surface and perspectively projecting the lens surface with the overlaid representation onto a plane spaced from the first and second viewpoints, respectively; and, (d) displaying the first and second transformed presentations on a display screen to generate the stereoscopic presentation.

This application is a continuation of U.S. patent application Ser. No. 10/289,453, filed Nov. 7, 2002, now U.S. Pat. No. 7,088,364 the disclosure of which is incorporated herein by reference.

This application claims priority from Canadian Patent Application No. 2,361,341 filed Nov. 7, 2001, the disclosure of which is incorporated herein by reference.

The invention relates to the field of computer graphics processing, and more specifically to a method and system for displaying stereoscopic detail-in-context presentations.

BACKGROUND OF THE INVENTION

Display screens are the primary interface for displaying information from a computer. Display screens are limited in size, thus presenting a challenge to graphical user interface design, particularly when large amounts of information are to be displayed. This problem is normally referred to as the “screen real estate problem”.

Well-known solutions to this problem include panning, zooming, scrolling or combinations thereof. While these solutions are suitable for a large number of visual display applications, these solutions become less effective where sections of the visual information are spatially related, such as maps, three-dimensional representations, newspapers and such like. In this type of information display, panning, zooming and/or scrolling is not as effective as much of the context of the panned, zoomed or scrolled display is hidden.

A recent solution to this problem is the application of “detail-in-context” presentation techniques. Detail-in-context is the magnification of a particular region of interest (the “focal region” or “detail”) in a data presentation while preserving visibility of the surrounding information (the “context”). This technique has applicability to the display of large surface area media, such as maps, on limited size computer screens including laptop computers, personal digital assistants (“PDAs”), and cell phones.

In the detail-in-context discourse, differentiation is often made between the terms “representation” and “presentation”. A representation is a formal system, or mapping, for specifying raw information or data that is stored in a computer or data processing system. For example, a digital map of a city is a representation of raw data including street names and the relative geographic location of streets and utilities. Such a representation may be displayed visually on a computer screen or printed on paper. On the other hand, a presentation is a spatial organization of a given representation that is appropriate for the task at hand. Thus, a presentation of a representation organizes such things as the point of view and the relative emphasis of different parts or regions of the representation. For example, a digital map of a city may be presented with a region magnified to reveal street names.

In general, a detail-in-context presentation may be considered as a distorted view (or distortion) of a portion of the original representation where the distortion is the result of the application of a “lens” like distortion function to the original representation. A detailed review of various detail-in-context presentation techniques such as Elastic Presentation Space may be found in a publication by Marianne S. T. Carpendale, entitled “A Framework for Elastic Presentation Space” (Carpendale, Marianne S. T., A Framework for Elastic Presentation Space (Burnaby, British Columbia: Simon. Fraser University, 1999)), and incorporated herein by reference.

In general, detail-in-context data presentations are characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (i.e. the context), the result typically giving the appearance of a lens having been applied to the display surface. Using the techniques described by Carpendale, points in a representation are displaced in three dimensions and a perspective projection is used to display the points on a two-dimensional presentation display.

In present detail-in-context presentation systems, when a lens is applied to a two-dimensional continuous surface representation, for example, the resulting presentation appears to be three-dimensional. In other words, the lens transformation appears to have stretched the continuous surface in a third dimension. In addition, shading the area transformed by the lens further reinforces the three-dimensional effect of the resulting presentation. Thus, in present systems, stretching and shading, two monocular perceptual cues, are used to provide an illusion of depth for detail-in-context presentations displayed on two-dimensional display screens.

One shortcoming of these detail-in-context presentation systems is that the monocular stretching and shading techniques do not generally yield effective three-dimensional effects for a range of presentations. This is especially so for presentations that include stereoscopically paired images or anaglyphs. For example, the ability to provide users with three-dimensional effects that are comfortable to view is of great value in extending the capabilities of detail-in-context presentations to applications involving essentially planar representations having data with relatively small depth differences. Such applications may include digital maps produced from stereoscopic satellite images.

A need therefore exists for the effective display of stereoscopic detail-in-context presentations in detail-in-context presentation systems. Consequently, it is an object of the present invention to obviate or mitigate at least some of the above mentioned disadvantages.

SUMMARY OF THE INVENTION

In general, the present invention provides for the effective presentation of stereoscopic detail-in-context presentations in detail-in-context presentation systems through the use of improved stereoscopic rendering techniques and an improved graphical user interface.

According to one aspect of this invention, there is provided a method for generating a stereoscopic presentation of a region-of-interest in a monoscopic information representation comprising the steps of: (a) selecting first and second viewpoints for the region-of-interest; (b) creating a lens surface having a predetermined lens surface shape for the region-of-interest, the lens surface having a plurality of polygonal surfaces constructed from a plurality of points sampled from the lens surface shape; (c) creating first and second transformed presentations by overlaying the representation on the lens surface and perspectively projecting the lens surface with the overlaid representation onto a plane spaced from the first and second viewpoints, respectively; and, (d) displaying the first and second transformed presentations on a display screen to generate the stereoscopic presentation.

According to another aspect of the invention, there is provided a method for generating a stereoscopic presentation of a region-of-interest in a stereoscopic information representation, the stereoscopic information representation including first and second images, comprising the steps of: (a) selecting a viewpoint for the region-of-interest; (b) creating a lens surface having a predetermined lens surface shape for the region-of-interest, the lens surface having a plurality of polygonal surfaces constructed from a plurality of points sampled from the lens surface shape; (c) creating first and second transformed presentations by overlaying the first and second images on the lens surface and perspectively projecting the lens surface with the overlaid first and second images onto a plane spaced from the viewpoint, respectively; and, (d) displaying the first and second transformed presentations on a display screen to generate the stereoscopic presentation.

According to another aspect of the invention, there is provided a method for generating a stereoscopic presentation of a region-of-interest in a stereoscopic information representation, the stereoscopic information representation including first and second images, comprising the steps of: (a) selecting first and second viewpoints for the region-of-interest; (b) creating a lens surface having a predetermined lens surface shape for the region-of-interest, the lens surface having a plurality of polygonal surfaces constructed from a plurality of points sampled from the lens surface shape; (c) creating first and second transformed presentations by overlaying the first and second images on the lens surface and perspectively projecting the lens surface with the overlaid first and second images onto a plane spaced from the first and second viewpoints, respectively; and, (d) displaying the first and second transformed presentations on a display screen to generate the stereoscopic presentation.

According to another aspect of the invention, there is provided a graphical user interface (GUI) for manipulating a stereoscopic presentation of a region-of-interest in an information representation displayed on a display screen of a computer display system, the computer display system including the display screen, a computer, and a pointing device for positioning a cursor on the display screen. The GUI includes: (a) a representation of a first slide bar, the first slide bar having a first active area, the first active area for adjusting a separation distance between first and second viewpoints for the region-of-interest by repositioning the first active area with the pointing device; (b) a representation of a second slide bar, the second slide bar having a second active area, the second active area for adjusting a height of a projection plane for generating the presentation above a basal plane by repositioning the second active area with the pointing device; and, (c) a representation of a third slide bar, the third slide bar having a third active area, the third active area for adjusting a height of GUI interface icons, including the first, second, and third slide bars, above the basal plane by repositioning the third active area with the pointing device.

According to another aspect of the invention, a stereoscopic presentation can be used for converting a raster representation to a vector representation by inversion of the stereoscopic presentation.

According to another aspect of the invention, a stereoscopic presentation can be used for editing or annotating a representation by inversion of the stereoscopic presentation.

Advantageously, the stereoscopic rendering method of the present invention may be applied to a wide variety of detail-in-context presentations. In particular, the present invention improves the presentation of three-dimensional detail-in-context effects in applications involving essentially planar representations having data with small depth differences (e.g. digital maps produced from stereoscopic satellite images). These stereoscopic rendering techniques of the present invention provide, for example, the effect or illusion that a lensed area of a presentation is protruding out of the display screen toward a user. A further advantage of the present invention is that through a graphical user interface, a user may quickly and easily adjust stereoscopic lens parameters for improved viewing comfort.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention may best be understood by referring to the following description and accompanying drawings. In the description and drawings, line numerals refer to like structures or processes. In the drawings:

FIG. 1 is a graphical representation of the geometry for constructing a three-dimensional (3D) perspective viewing frustum, relative to an x, y, z coordinate system, in accordance with known elastic presentation space graphics technology;

FIG. 2 is a graphical representation of the geometry of a presentation in accordance with known elastic presentation space graphics technology;

FIG. 3 is a block diagram illustrating an exemplary data processing system for implementing an embodiment of the invention;

FIG. 4 a partial screen capture illustrating a graphical user interface having lens control elements for user interaction with stereoscopic detail-in-context data presentations in accordance with an embodiment of the invention;

FIG. 5 is a graphical representation of the geometry for constructing stereoscopic perspective viewing frustums in accordance with an embodiment of the invention; and,

FIG. 6 is a flow chart illustrating a general method for a general method for generating a stereoscopic presentation of a region-of-interest in a monoscopic information representation in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known software, circuits, structures and techniques have not been described or shown in detail in order not to obscure the invention. In the drawings, like numerals refer to like structures or processes.

The term “data processing system” is used herein to refer to any machine for processing data, including the computer systems and network arrangements described herein. The term “Elastic Presentation Space” (“EPS”) (or “Pliable Display Technology” (“PDT”)) is used herein to refer to techniques that allow for the adjustment of a visual presentation without interfering with the information content of the representation. The adjective “elastic” is included in the term as it implies the capability of stretching and deformation and subsequent return to an original shape. EPS graphics technology is described by Carpendale in “A Framework for Elastic Presentation Space” (Carpendale, Marianne S. T., A Framework for Elastic Presentation Space (Burnaby, British Columbia: Simon Fraser University, 1999)), which is incorporated herein by reference. In EPS graphics technology, a two-dimensional visual representation is placed onto a surface; this surface is placed in three-dimensional space; the surface, containing the representation, is viewed through perspective projection; and the surface is manipulated to effect the reorganization of image details. The presentation transformation is separated into two steps: surface manipulation or distortion and perspective projection.

FIG. 1 is a graphical representation 100 of the geometry for constructing a three-dimensional (“3D”) perspective viewing frustum 220, relative to an x, y, z coordinate system, in accordance with known elastic presentation space (EPS) graphics technology. In EPS technology, detail-in-context views of two-dimensional (“2D”) visual representations are created with sight-line aligned distortions of a 2D information presentation surface within a 3D perspective viewing frustum 220. In EPS, magnification of regions of interest and the accompanying compression of the contextual region to accommodate this change in scale are produced by the movement of regions of the surface towards the viewpoint (“VP”) 240 located at the apex of the pyramidal shape 220 containing the frustum. The process of projecting these transformed layouts via a perspective projection results in a new 2D layout which includes the zoomed and compressed regions. The use of the third dimension and perspective distortion to provide magnification in EPS provides a meaningful metaphor for the process of distorting the information presentation surface. The 3D manipulation of the information presentation surface in such a system is an intermediate step in the process of creating a new 2D layout of the information.

FIG. 2 is a graphical representation 200 of the geometry of a presentation in accordance with known EPS graphics technology. EPS graphics technology employs viewer-aligned perspective projections to produce detail-in-context presentations in a reference view plane 201 which may be viewed on a display. Undistorted 2D data points are located in a basal plane 210 of a 3D perspective viewing volume or frustum 220 which is defined by extreme rays 221 and 222 and the basal plane 210. The VP 240 is generally located above the centre point of the basal plane 210 and reference view plane (“RVP”) 201. Points in the basal plane 210 are displaced upward onto a distorted surface 230 which is defined by a general 3D distortion function (i.e. a detail-in-context distortion basis function). The direction of the viewer-aligned perspective projection corresponding to the distorted surface 230 is indicated by the line FPo-FP 231 drawn from a point FPo 232 in the basal plane 210 through the point FP 233 which corresponds to the focus or focal region or focal point of the distorted surface 230.

EPS is applicable to multidimensional data and is well suited to implementation on a computer for dynamic detail-in-context display on an electronic display surface such as a monitor. In the case of two dimensional data, EPS is typically characterized by magnification of areas of an image where detail is desired 233, in combination with compression of a restricted range of areas of the remaining information (i.e. the context) 234, the end result typically giving the appearance of a lens 230 having been applied to the display surface. The areas of the lens 230 where compression occurs may be referred to as the “shoulder” 234 of the lens 230. The area of the representation transformed by the lens may be referred to as the “lensed area”. The lensed area thus includes the focal region and the shoulder. To reiterate, the source image or representation to be viewed is located in the basal plane 210. Magnification 233 and compression 234 are achieved through elevating elements of the source image relative to the basal plane 210, and then projecting the resultant distorted surface onto the reference view plane 201. EPS performs detail-in-context presentation of n-dimensional data through the use of a procedure wherein the data is mapped into a region in an (n+1) dimensional space, manipulated through perspective projections in the (n+1) dimensional space, and then finally transformed back into n-dimensional space for presentation. EPS has numerous advantages over conventional zoom, pan, and scroll technologies, including the capability of preserving the visibility of information outside 234 the local region of interest 233.

For example, and referring to FIGS. 1 and 2, in two dimensions, EPS can be implemented through the projection of an image onto a reference plane 201 in the following manner. The source image or representation is located on a basal plane 210, and those regions of interest 233 of the image for which magnification is desired are elevated so as to move them closer to a reference plane situated between the reference viewpoint 240 and the reference view plane 201. Magnification of the focal region 233 closest to the RVP 201 varies inversely with distance from the RVP 201. As shown in FIGS. 1 and 2, compression of regions 234 outside the focal region 233 is a function of both distance from the RVP 201, and the gradient of the function describing the vertical distance from the RVP 201 with respect to horizontal distance from the focal region 233. The resultant combination of magnification 233 and compression 234 of the image as seen from the reference viewpoint 240 results in a lens-like effect similar to that of a magnifying glass applied to the image. Hence, the various functions used to vary the magnification and compression of the source image via vertical displacement from the basal plane 210 are described as lenses, lens types, or lens functions. Lens functions that describe basic lens types with point and circular focal regions, as well as certain more complex lenses and advanced capabilities such as folding, have previously been described by Carpendale.

System. FIG. 3 is a block diagram of an exemplary data processing system 300 for implementing an embodiment of the invention. The data processing system is suitable for implementing EPS technology and for viewing stereoscopic presentations in conjunction with a graphical user interface (“GUI”). The data processing system 300 includes an input device 310, a central processing unit or CPU 320, memory 330, and a display 340. The input device 310 may include a keyboard, mouse, trackball, or similar device. The CPU 320 may include dedicated coprocessors and memory devices. The memory 330 may include RAM, ROM, databases, or disk devices. And, the display 340 may include a computer screen or terminal device and a stereoscopic viewing device (not shown). The stereoscopic viewing device may include a pair of 3D anaglyph (i.e. red/blue, red/green, etc.) glasses or a pair of 3D shutter glasses with supporting hardware and software. The display 340 may also include split level screens. The data processing system 300 has stored therein data representing sequences of instructions which when executed cause the method described herein to be performed. Of course, the data processing system 300 may contain additional software and hardware a description of which is not necessary for understanding the invention.

Stereoscopic Detail-In-Context Presentations from Monoscopic Images. FIG. 5 is a graphical representation 500 of the geometry for constructing stereoscopic perspective viewing frustums in accordance with an embodiment of the invention. In FIG. 5, the right-eye and left-eye viewpoints 541, 542 lie at the apex of right-eye and left-eye perspective viewing frustums 521, 522, respectively. The right-eye and left-eye viewpoints 541, 542 are spaced by an “eye separation” distance 501.

According to an embodiment of the invention, stereoscopic detail-in-context presentations are generated from monoscopic images. In general, a monoscopic representation of a 3D object is rendered or presented stereoscopically by rendering the representation twice, once from a right-eye viewpoint 541 and once from a left-eye viewpoint 542. If no lens is applied to the representation, the right and left renderings are generally the same (i.e. for images that are not stereo pairs). If a lens is applied, the required point displacements are calculated by software stored in the data processing system 300 and stored as 3D coordinates in the system's memory 330. These newly displaced points are then rendered or projected twice using separate perspective viewing volumes or frustums 521, 522. The rendered images are then overlaid (or interlaced) to produce the final presentation for display to the user. In general, this point displacement or transformation operation includes the generation of a 3D mesh or polygonal surface grid, produced by sampling from the shape of the surface corresponding to the lens or 3D distortion function, and the overlaying or texture-mapping of the representation onto this 3D mesh to produce the required point displacements. The generation of 3D meshes is described in U.S. patent application Ser. No. 09/978,773, filed by the present applicant, and incorporated herein by reference. Advantageously, processing time is saved in this embodiment of the invention by using only one transformation operation followed by two projection operations.

In general, when viewed without a stereoscopic viewing device, the area 233, 234 within the lens 230 appears as doubled to the user. The distance between a point rendered by the right viewing volume 521 and the same point rendered with the left viewing volume 522 may be referred to as “parallax”. The greater the parallax, the more the object appears to a user to be protruding from the plane of the display screen 340. The degree or amount of parallax is affected by the height of a data point above the basal plane 210, or more generally by the distance of the data point from the projection plane 201, and the horizontal distance between the viewpoints 541, 542 of the two perspective viewing volumes, that is, the eye separation 501. As described by Valyrus in. “Stereoscopy” (Valyrus, N. A., Stereoscopy, London: Focal Press, 1966), which is incorporated herein by reference, too much parallax in a presentation can be uncomfortable for a user to view. In general, parallax will be at a maximum in the focal region 233 of a lens 230.

Typically, a representation that is viewed through a lens presentation has a finite resolution. Given this resolution, software stored in the system 300 calculates the maximum height of the lens corresponding to the maximum level of magnification for this resolution. In general, the maximum height is measured from the basal plane 210. The lens height may be readily determined given a predetermined or user selected magnification level. Using this maximum height, the software adjusts the eye separation 501 such that the maximum parallax will not be uncomfortable to a user when viewing the presentation. It is, of course, difficult to determine when an individual user's comfort level will be exceeded. For example, some users may be comfortable with only a small level of parallax. Experimentally, it has been determined that having parallax levels greater than one-half inch (i.e. when the display screen is viewed from a distance of approximately 1.5 feet) is uncomfortable for many users. In this respect, refer again to Valyrus (Valyrus, N. A., Stereoscopy, London, New York: Focal Press, 1962; incorporated herein by reference). As will be described below, if a user is comfortable with larger parallax levels, the user can adjust eye separation 501 manually.

For representations that have infinite resolution, vector data for example, the maximum height of the lens is chosen based on a predetermined maximum amount of compression for the shoulder region 234 of the lens 230 for a predetermined average lens size (i.e. lensed area). Again, a user may adjust eye separation 501 manually.

Stereoscopic Detail-In-Context Presentations from Stereoscopic Images. According to an embodiment of the invention, stereoscopic detail-in-context presentations are generated from stereoscopic images (i.e. stereoscopically paired images). In general, lenses are applied to representations consisting of stereoscopically paired images by displacing the points on both images and rendering the left and right images consecutively using perspective projection. The rendered images are then overlaid (or interlaced) to produce the final presentation for display to the user. Here, one perspective viewing volume 220 is used, two stereo images are displaced onto a single 3D mesh, and the mesh is viewed monoscopically. In this case, parallax derives from the stereo images but not from the height of the lenses. Advantageously, processing time is saved by calculating the displacements only once, using a finitely subdivided 3D mesh, and then consecutively texture-mapping the right and left images on this mesh. That is, rather than requiring two 3D meshes (i.e. one for each image), one 3D mesh is generated corresponding to the lens and this is followed by two texture-mapping operations which consecutively overlay each original image on the mesh. These operations are then followed by a projection operation for each image using a single perspective viewing volume 220.

When viewed with a stereoscopic viewing device, the resultant images will have their original stereo effect where they are not distorted by the lens. In the lensed area, the stereo effect will be intensified in the focal region 233 and generally reduced in the shoulder region 234. In general, only the areas of the shoulder 234 that compress the data horizontally will decrease the parallax. In the shoulder region 234, the perception of depth will be affected by the steepness of the shoulder.

For representations consisting of stereoscopically paired images, the maximum parallax may be adjusted by the software to account for the additional parallax that will result when the lens transformation is applied to the original stereoscopic representation. In this situation, the software may decrease the eye separation 501. In general, the method described above for monoscopic images is used to adjust the parallax, but rather than using the maximum height of the lens, the maximum (or average) parallax present in the image itself is used. For example, consider a stereo image that includes an image of a building where the building protrudes from the stereo image. At full magnification, the parallax level must be comfortable for a user. If the building is higher than the lens (i.e. in the focal region), then if the eye separation 501 is adjusted such that viewing of the building is comfortable to a user, then, the lens will also be comfortable to view. In addition, because viewing discomfort varies from user to user, the system 300 includes means such as a GUI and mouse input device 310 to allow users to manually adjust eye separation 501. This GUI is described in more detail below.

Alternatively, a red/blue (or, red/green, etc.) anaglyph may be created from the stereoscopically paired images and rendered using the method described above for monoscopic images. In general, an anaglyph is an image consisting of two slightly different perspectives (e.g. right and left eye views) of the same object in contrasting colours (e.g. red and blue) that are superimposed on each other, producing a 3D effect when viewed through two correspondingly coloured filters. An advantage of this alternative is that the stereoscopic viewing device may consist of a simple pair of 3D anaglyph (i.e. red/blue, red/green, etc.) glasses rather than more complex 3D shutter glasses. Anaglyphs may be created using readily available off-the-shelf software.

Stereoscopic Detail-In-Context Presentations with Stereoscopic Lenses. According to an embodiment of the invention, stereoscopic detail-in-context presentations with stereoscopic lenses are generated from stereoscopic images. Generally, viewing stereoscopically paired images with non-stereoscopic lenses may be incongruous. The lack of depth in the lenses may be disturbing to the user because while the user is accustomed to perceiving depth in the original stereoscopic image, and while there are strong monocular cues that the lens is 3D, the appearance of the 3D effects in the lensed area may differ from the appearance of the 3D effects outside of the lensed area. Advantageously, the stereo viewing methods described can be combined to view stereoscopically paired images with stereoscopically rendered lenses to reduce this incongruity. Here, two perspective viewing volumes 521, 522 are used, two stereo images are displaced onto a single 3D mesh, and the mesh is viewed stereoscopically. In this case, parallax derives from both the stereo images and from the height of the lenses.

In general, stereoscopic lenses are rendered such that the zero parallax setting (“ZPS”) of the original image is lifted by the height of the lens 230 in the focal 233 and shoulder 234 regions. The ZPS is that height above the basal plane of the original images where the distance between a point in the first or right view 541 and the same point in the second or left view 542 is zero. In general, ZPS corresponds to the projection plane 201 where, conceptually, there should be no perceived height. In effect, if an area of the original image appeared to be sunk into the display screen when viewed by a user, that area will appear to be sunk into the lens. Similarly, if an area of the original image appeared to be protruding from the display screen, it will appear to be protruding from the lens. Note that the eye separation 501 used for the stereoscopic lenses will not affect the parallax of the resultant image or presentation. The eye separation 501 only influences the depth perception of the lenses. In this case, as each stereoscopic image is laid over a mesh, which is then viewed stereoscopically, there is a ZPS associated with the original images and a ZPS associated with the stereoscopically viewed mesh. These ZPSs may be referred to as the image ZPS and the mesh ZPS, respectively. Again, because viewing discomfort varies from user to user, the system 300 includes means such as a GUI and mouse input device 310 to allow users to manually adjust parameters including eye separation, image ZPS, and mesh ZPS.

GUI with Stereoscopic Lens Control Elements. GUIs for non-stereo detail-in-context presentations are described in U.S. patent application Ser. Nos. 10/137,648 and 10/166,736, filed by the present applicant, and incorporated herein by reference. Generally, with a GUI, a user interacts with icons and controls in a GUI display by moving a pointing device, such as a mouse, which causes a cursor or pointer to be moved on the display. When the pointer is over the displayed icon or control, the user presses a button, such as a mouse button, to invoke one or more operations to be performed by the computer system. In the following, a GUI having lens control elements that can be implemented in software and applied to the control of stereoscopic detail-in-context data presentations is described. The software can be loaded into and run by the data processing system 300 of FIG. 3.

FIG. 4 is a partial screen capture illustrating a GUI 400 having lens control elements for user interaction with stereoscopic detail-in-context data presentations in accordance with an embodiment of the invention. As mentioned above, detail-in-context data presentations are characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (i.e. the context), the end result typically giving the appearance of a lens having been applied to the display screen surface. This stereoscopic lens 410 includes a focal region 420 having high magnification, a surrounding shoulder region 430 where information is typically visibly compressed, and a base 412 surrounding the shoulder region 430 and defining the extent of the lens 410. In FIG. 4, the lens 410 is shown with a circular shaped base 412 (or outline) and with a focal region 420 lying near the center of the lens 410. However, the lens 410 and focal region 420 may have any desired shape. Referring again to FIG. 2, in general, the stereoscopic lens 410 corresponds to projections of the distorted surface 230, focal region 233, and shoulder region 234 onto the reference view plane 201.

In general, the GUI 400 has lens control elements that, in combination, provide for the interactive control of the lens 410. The effective control of the characteristics of the lens 410 by a user (i.e. dynamic interaction with a detail-in-context lens) is advantageous. At any given time, one or more of these lens control elements may be made visible to the user on the display surface 340 by appearing as overlay icons on the lens 410. Interaction with each element is performed via the motion of a pointing device 310 (e.g. mouse), with the motion resulting in an appropriate change in the corresponding lens characteristic. As will be described, selection of which lens control element is actively controlled by the motion of the pointing device 310 at any given time is determined by the proximity of the icon representing the pointing device 310 on the display surface 340 (e.g. cursor) to the appropriate component of the lens 410. For example, “dragging” of the pointing device at the periphery of the bounding rectangle of the lens base 412 causes a corresponding change in the size of the lens 410 (i.e. “resizing”). Thus, the GUI 400 provides the user with a visual representation of which lens control element is being adjusted through the display of one or more corresponding icons.

For ease of understanding, the following discussion will be in the context of using a two-dimensional pointing device 310 that is a mouse, but it will be understood that the invention may be practised with other 2-D or 3-D (or even greater numbers of dimensions) pointing devices including a trackball and keyboard.

A mouse 310 controls the position of a cursor icon 401 that is displayed on the display screen 340. The cursor 401 is moved by moving the mouse 310 over a flat surface, such as the top of a desk, in the desired direction of movement of the cursor 401. Thus, the two-dimensional movement of the mouse 310 on the flat surface translates into a corresponding two-dimensional movement of the cursor 401 on the display screen 340.

A mouse 310 typically has one or more finger actuated control buttons (i.e. mouse buttons). While the mouse buttons can be used for different functions such as selecting a menu option pointed at by the cursor 401, the disclosed invention may use a single mouse button to “select” a lens 410 and to trace the movement of the cursor 401 along a desired path. Specifically, to select a lens 410, the cursor 401 is first located within the extent of the lens 410. In other words, the cursor 401 is “pointed” at the lens 410. Next, the mouse button is depressed and released. That is, the mouse button is “clicked”. Selection is thus a point and click operation. To trace the movement of the cursor 401, the cursor 401 is located at the desired starting location, the mouse button is depressed to signal the computer 320 to activate a lens control element, and the mouse 310 is moved while maintaining the button depressed. After the desired path has been traced, the mouse button is released. This procedure is often referred to as “clicking” and “dragging” (i.e. a click and drag operation). It will be understood that a predetermined key on a keyboard 310 could also be used to activate a mouse click or drag. In the following, the term “clicking” will refer to the depression of a mouse button indicating a selection by the user and the term “dragging” will refer to the subsequent motion of the mouse 310 and cursor 401 without the release of the mouse button.

The GUI 400 may include the following lens control elements: move, pickup, resize base, resize focus, fold, magnify, and zoom. According to an embodiment of the present invention, the GUI 400 may include the following additional lens control elements that are applicable to stereoscopic detail-in-context presentations: GUI height, eye separation, image ZPS, and mesh ZPS. Each of these lens control elements generally has at least one lens control icon or alternate cursor icon associated with it. In general, when a lens 410 is selected by a user through a point and click operation, the following lens control icons may be displayed over the lens 410: pickup icon 450, base outline icon 412, base bounding rectangle icon 411, focal region bounding rectangle icon 421, handle icons 481, 482, 491, magnify slide bar icon 440, and zoom icon 495. In addition, GUI height, eye separation, image ZPS, and mesh ZPS icons (not shown) may be displayed over the lens 410 or on a toolbar or pull-down menu. Typically, these icons are displayed simultaneously after selection of the lens 410. In addition, when the cursor 401 is located within the extent of a selected lens 410, an alternate cursor icon (e.g. 460, 470, 480, 490, 496) may be displayed over the lens 410 to replace the cursor 401 or may be displayed in combination with the cursor 401. In addition, when GUI height, eye separation, image ZPS, or mesh ZPS functionality is selected by the user, for example, through a toolbar or pull-down menu, corresponding alternate cursor icons (note shown) may be displayed to replace the cursor 401 or may be displayed in combination with the cursor 401. The move, pickup, resize base, resize focus, fold, magnify, and zoom lens control elements are described in U.S. patent application Ser. Nos. 10/137,648 and 10/166,736 mentioned above. The GUI height, eye separation, image ZPS, and mesh ZPS lens control elements and their effects on the characteristics of a lens 410 are described below.

In general, when a lens 410 is selected by a point and click operation, bounding rectangle icons 411, 421 are displayed surrounding the base 412 and focal region 420 of the selected lens 410 to indicate that the lens 410 has been selected. With respect to the bounding rectangles 411, 421 one might view them as glass windows enclosing the lens base 412 and focal region 420, respectively. The bounding rectangles 411, 421 include handle icons 481, 482, 491 allowing for direct manipulation of the enclosed base 412 and focal region 420. Thus, the bounding rectangles 411, 421 not only inform the user that the lens 410 has been selected, but also provide the user with indications as to what manipulation operations might be possible for the selected lens 410 though use of the displayed handles 481, 482, 491. Note that it is well within the scope of the present invention to provide a bounding region having a shape other than generally rectangular. Such a bounding region could be of any of a great number of shapes including oblong, oval, ovoid, conical, cubic, cylindrical, polyhedral, spherical, etc. Moreover, the cursor 401 provides a visual cue indicating the nature of an available lens control element. As such, the cursor 401 will generally change in form by simply pointing to or selecting a different lens control icon (e.g. 450, 412, 411, 421, 481, 482, 491, 440, 495). For example, when resizing the base 412 of a lens 410 using a corner handle 491, the cursor 401 will change form to a resize icon 490 once it is pointed at (i.e. positioned over) the corner handle 491. The cursor 401 will remain in the form of the resize icon 490 until the cursor 401 has been moved away from the corner handle 491.

GUI Height. In general, because the focal region 233 of a stereoscopic lens 410 appears to be protruding from the display screen when viewed by a user, the lens control icons (e.g. 450, 412, 411, 421, 481, 482, 491, 440, 495) of the GUI 400 are rendered in stereo so that these lens control icons appear at the same height as the focal region 233. This is accomplished by elevating the lens control icons by a predetermined or user selected amount and rendering them twice, once using a left-eye viewing volume, and again using a right-eye viewing volume. The same viewing volumes used to render the stereoscopic lens may be used. The predetermined or default height for the top of the lens control icons of the GUI may be set by the software to the height of the top of the lens.

User adjustment of the height of the lens control icons of the GUI 400 relative to the height of the lens 410 is provided by the GUI height lens control element of the GUI. After the lens 410 is selected, the GUI height control element is presented to the user as a slide bar icon (not shown) near or adjacent to the lens 410 and typically to one side of the lens 410. Sliding the bar (not shown) of the slide bar results in a proportional change in the height of the lens control icons of the GUI relative to the height of the lens 410. The slide bar not only informs the user that the height of the control icons of the GUI may be selected, but also provides the user with an indication as to what level of height control is possible. The slide bar includes a bar that may be slid up and down, or left and right, to adjust and indicate the height of the lens control icons of the GUI. To adjust the height of the lens control icons, the user would click on the bar of the slide bar and drag in the direction of desired height. Once the desired height is reached, the user would release the mouse button 310. The lens 410 is then locked with the selected height for the lens control icons until a further GUI height operation is performed.

Alternatively, rather than using a slide bar icon to implement the GUI height function, a GUI height function menu with multiple items (not shown) or multiple GUI height function icons (not shown) may be used for GUI height selection. The GUI height function menu may be presented as a pull-down menu. The GUI height function icons may be presented in a toolbar or adjacent to the lens 410 when the lens is selected. Individual GUI height menu items or GUI height function icons may be provided for predetermined GUI heights. In this alternative, after the lens 410 is selected, a bounding rectangle icon 411 may be displayed surrounding the base 412 and a bounding rectangle icon 421 may be displayed surrounding the focal region 420. GUI height adjustment functionality is accomplished by the user selecting a GUI height from the GUI height function menu or via the GUI height function icons using a point and click operation. In this way, a GUI height function may be selected without considering the position of the cursor 401 within the lens 410.

Eye Separation. Eye separation 501 may be predetermined or user selected. The predetermined or default eye separation 501 may be set by the software to provide a parallax level, for example, of one half inch (i.e. when the display screen is viewed from a distance of 1.5 feet).

User adjustment of the eye separation 501 for the lens 410 is provided by the eye separation lens control element of the GUI. After the lens 410 is selected, the eye separation control element is presented to the user as a slide bar icon (not shown) near or adjacent to the lens 410 and typically to one side of the lens 410. Sliding the bar (not shown) of the slide bar results in a proportional change in the eye separation of the lens 410. The slide bar not only informs the user that the eye separation may be selected, but also provides the user with an indication as to what level of eye separation control is possible. The slide bar includes a bar that may be slid up and down, or left and right, to adjust and indicate the eye separation. To adjust the eye separation for the lens, the user would click on the bar of the slide bar and drag in the direction of desired eye separation. Once the desired eye separation is reached, the user would release the mouse button 310. The lens 410 is then locked with the selected eye separation until a further eye separation operation is performed.

Alternatively, rather than using a slide bar icon to implement the eye separation function, an eye separation function menu with multiple items (not shown) or multiple eye separation function icons (not shown) may be used for eye separation selection. The eye separation function menu may be presented as a pull-down menu. The eye separation function icons may be presented in a toolbar or adjacent to the lens 410 when the lens is selected. Individual eye separation menu items or eye separation function icons may be provided for predetermined eye separations. In this alternative, after the lens 410 is selected, a bounding rectangle icon 411 may be displayed surrounding the base 412 and a bounding rectangle icon 421 may be displayed surrounding the focal region 420. Eye separation adjustment functionality is accomplished by the user selecting an eye separation from the eye separation function menu or via the eye separation function icons using a point and click operation. In this way, an eye separation function may be selected without considering the position of the cursor 401 within the lens 410.

Image ZPS. In general, varying the horizontal offset of the images on the mesh used to produce a stereoscopic lens, varies the ZPS of the images. The image ZPS may be predetermined or user selected. Adjusting the image ZPS is important for images that have a wide parallax range. In general, the predetermined or default image ZPS may be set by the software to correspond to a parallax level lying in the middle of the parallax range for the image.

User adjustment of the image ZPS for the lens 410 is provided by the image ZPS lens control element of the GUI. After the lens 410 is selected, the image ZPS control element is presented to the user as a slide bar icon (not shown) near or adjacent to the lens 410 and typically to one side of the lens 410. Sliding the bar (not shown) of the slide bar results in a proportional change in the image ZPS of the lens 410. The slide bar not only informs the user that the image ZPS may be selected, but also provides the user with an indication as to what level of image ZPS control is possible. The slide bar includes a bar that may be slid up and down, or left and right, to adjust and indicate the image ZPS. To adjust the image ZPS for the lens, the user would click on the bar of the slide bar and drag in the direction of desired image ZPS. Once the desired image ZPS is reached, the user would release the mouse button 310. The lens 410 is then locked with the selected image ZPS until a further image ZPS operation is performed.

Alternatively, rather than using a slide bar icon to implement the image ZPS function, an image ZPS function menu with multiple items (not shown) or multiple image ZPS function icons (not shown) may be used for image ZPS selection. The image ZPS function menu may be presented as a pull-down menu. The image ZPS function icons may be presented in a toolbar or adjacent to the lens 410 when the lens is selected. Individual image ZPS menu items or image ZPS function icons may be provided for predetermined image ZPSs. In this alternative, after the lens 410 is selected, a bounding rectangle icon 411 may be displayed surrounding the base 412 and a bounding rectangle icon 421 may be displayed surrounding the focal region 420. Image ZPS adjustment functionality is accomplished by the user selecting an image ZPS from the image ZPS function menu or via the image ZPS function icons using a point and click operation. In this way, an image ZPS function may be selected without considering the position of the cursor 401 within the lens 410.

Mesh ZPS. In general, varying the horizontal offset of the mesh, varies the ZPS of the mesh. Because the images are texture-mapped onto the mesh to produce a stereoscopic lens, when the ZPS of the mesh is changed, the ZPS of the stereoscopic image stays constant in relation to it. That is, even if the mesh is moved into the display screen, all objects that originally appeared to be above the mesh will still appear to be above the mesh. Varying the ZPS of the mesh can be used as an alternative to adjusting the eye separation when the parallax for the lens is uncomfortably large. The mesh ZPS may be predetermined or user selected. For example, the predetermined or default mesh ZPS may be set by the software to correspond to a parallax level lying in the middle of the parallax range for the mesh.

User adjustment of the mesh ZPS for the lens 410 is provided by the mesh ZPS lens control element of the GUI. After the lens 410 is selected, the mesh ZPS control element is presented to the user as a slide bar icon (not shown) near or adjacent to the lens 410 and typically to one side of the lens 410. Sliding the bar (not shown) of the slide bar results in a proportional change in the mesh ZPS of the lens 410. The slide bar not only informs the user that the mesh ZPS may be selected, but also provides the user with an indication as to what level of mesh ZPS control is possible. The slide bar includes a bar that may be slid up and down, or left and right, to adjust and indicate the mesh ZPS. To adjust the mesh ZPS for the lens, the user would click on the bar of the slide bar and drag in the direction of desired mesh ZPS. Once the desired mesh ZPS is reached, the user would release the mouse button 310. The lens 410 is then locked with the selected mesh ZPS until a further mesh ZPS operation is performed.

Alternatively, rather than using a slide bar icon to implement the mesh ZPS function, a mesh ZPS function menu with multiple items (not shown) or multiple mesh ZPS function icons (not shown) may be used for mesh ZPS selection. The mesh ZPS function menu may be presented as a pull-down menu. The mesh ZPS function icons may be presented in a toolbar or adjacent to the lens 410 when the lens is selected. Individual mesh ZPS menu items or mesh ZPS function icons may be provided for predetermined mesh ZPSs. In this alternative, after the lens 410 is selected, a bounding rectangle icon 411 may be displayed surrounding the base 412 and a bounding rectangle icon 421 may be displayed surrounding the focal region 420. Mesh ZPS adjustment functionality is accomplished by the user selecting a mesh ZPS from the mesh ZPS function menu or via the mesh ZPS function icons using a point and click operation. In this way, a mesh ZPS function may be selected without considering the position of the cursor 401 within the lens 410.

In addition, the GUI 400 maintains a record of GUI height, eye separation, image ZPS, and mesh ZPS operations such that the user may restore pre-GUI height, eye separation, image ZPS, and mesh ZPS operation presentations. This record of operations may be accessed by or presented to the user through “Undo” and “Redo” icons 497, 498 or a pull-down operation history menu (not shown).

Method. FIG. 6 is a flow chart 600 illustrating a general method for generating a stereoscopic presentation of a region-of-interest in a monoscopic information representation in accordance with an embodiment of the invention. At step 601, the method starts. At step 602, first and second viewpoints for the region-of-interest are selected. At step 603, a transformation is applied to the representation to improve the visual detail in the region-of-interest by: creating a lens surface having a predetermined lens surface shape for the region-of-interest, wherein the lens surface is comprised of a plurality of polygonal surfaces constructed from a plurality of points sampled from the lens surface shape; and, creating first and second transformed presentations by overlaying the representation on the lens surface and perspectively projecting the lens surface with the overlaid representation onto a plane from the first and second viewpoints, respectively. At step 604, the first and second transformed presentations are displayed on a display screen, thereby generating the stereoscopic presentation. At step 605, the method ends.

Applications. In general, stereo lenses can be used in any application that uses non-stereo lenses. If stereo hardware is available, it can be more intuitive for a user to work with stereo lenses even on mono images. Of course, applications that already use stereoscopic image pairs will directly benefit from the present invention. Consider applications involving stereo satellite images. Viewing these images with the aid of stereo lens is particularly beneficial because these images are based on mainly planar data having small depth differences. Stereo lenses may be used in any EPS based application which range from marketing to training. In general, stereo lenses provide benefits in navigating or enhancing computer-generated 3D spaces or worlds.

Stereoscopic presentations generated in accordance with the present invention may be combined with detail-in-context inversion techniques, as described in U.S. patent application Ser. No. 09/932,088 and Canadian Patent Application No. 2,386,702, filed by the present applicant, and incorporated herein by reference, to perform vector data collection or vector data conversion from stereoscopic data sets including raster imagery stereo pairs from remote sensing data sources.

Similarly, stereoscopic presentations generated in accordance with the present invention may be combined with these detail-in-context inversion techniques to perform data editing or annotation on presented data.

Data Carrier Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of FIG. 3 can be contained in a data carrier product according to one embodiment of the invention. This data carrier product can be loaded into and run by the exemplary data processing system of FIG. 3.

Computer Software Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of FIG. 3 can be contained in a computer software product according to one embodiment of the invention. This computer software product can be loaded into and run by the exemplary data processing system of FIG. 3.

Integrated Circuit Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of FIG. 3 can be contained in an integrated circuit product including a coprocessor or memory according to one embodiment of the invention. This integrated circuit product can be installed in the exemplary data processing system of FIG. 3.

Although preferred embodiments of the invention have been described herein, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims. 

1. A system comprising: a processor coupled to memory; and one or more modules stored within the memory and executable by the processor to: construct a lens having a plurality of polygonal surfaces according to a lens function; generate a stereoscopic presentation of a region-of-interest within an information representation of a digital image, the stereoscopic presentation including a stereoscopic distortion of the digital image in the region-of-interest surrounded by undistorted portions of the digital image outside of the region-of-interest by: overlaying first and second images of the information representation onto the constructed lens to create the stereoscopic distortion of the digital image for the region-of-interest; and perspectively projecting the constructed lens having the overlaid first and second images onto a plane in first and second directions aligned with first and second viewpoints for the region-of-interest, respectively; render a graphical user interface (“GUI”) over the region-of-interest for receiving one or more signals for adjusting the lens; and output the stereoscopic presentation for display on a display screen.
 2. The system of claim 1 wherein the first and second viewpoints are separated by a distance.
 3. The system of claim 2, wherein the one or more modules are executable to receive a signal indicative of the distance through the graphical user interface (“GUI”).
 4. The system of claim 1 wherein the plane is spaced at a height above a basal plane.
 5. The system of claim 4, wherein the one or more modules are executable to receive a signal indicative of the height through the graphical user interface (“GUI”).
 6. The system of claim 1 wherein the plane includes a first plane for the lens and a second plane for the stereoscopic distortion.
 7. The system of claim 6 wherein the first and second planes are spaced at first and second heights, respectively, above a basal plane.
 8. The system of claim 7, wherein the one or more modules are executable to receive first and second signals indicative, respectively, of the first and second heights through the graphical user interface (“GUI”).
 9. The system of claim 1 wherein: the lens includes a focal region at least partially surrounded by a base region; the stereoscopic distortion comprises a magnification of the digital image in the focal region; and a magnification level varies across the base region to provide a continuous transition from the magnification of the digital image in the focal region to the undistorted portions of the digital image outside of the region-of-interest.
 10. The system of claim 9 wherein the focal region has a size and a shape and further comprising a module for receiving one or more signals to adjust at least one of the size, the shape, and the magnification of the digital image in the focal region.
 11. The system of claim 1 wherein the one or more signals are received through control elements exposed in the GUI.
 12. The system of claim 11 wherein the control elements exposed in the GUI include control elements for adjusting at least one of a size, a shape, and a magnification of the region-of-interest.
 13. The system of claim 12 wherein at least some of the control elements are icons.
 14. The system of claim 12 wherein the control elements include at least one handle icon positioned on a perimeter of the GUI for adjusting the size and the shape of the region-of-interest.
 15. The system of claim 12 wherein the control elements include a slide bar icon for adjusting the magnification of the region-of-interest.
 16. The system of claim 10 wherein the one or more signals are generated by an input device coupled to the system and operable to move a cursor on the display screen.
 17. The system of claim 9 wherein the base region has a size and a shape and the one or more modules are executable to receive one or more signals through the GUI to adjust at least one of the size and the shape of the base region, wherein the GUI has one or more handle icons positioned on a perimeter of the base region for adjusting at least one of the size and the shape of the base region.
 18. The system of claim 9 wherein the GUI comprises at least one of: a slide bar icon for adjusting the magnification; a bounding rectangle icon with at least one handle icon for adjusting a size and a shape for the focal region; a bounding rectangle icon with at least one handle icon for adjusting a size and a shape for the base region; a move icon for adjusting a location for the lens; a pickup icon for adjusting a location for the base region; or, a fold icon for adjusting a location for the focal region relative to the base region to define a folding of the focal region over the base region.
 19. The system of claim 1 wherein the information representation is a raster representation and the one or more modules are executable to convert the raster representation to a vector representation by inversion of the stereoscopic presentation.
 20. The system of claim 1, wherein the one or more modules are executable to receive signals indicative of at least one of editing and annotating instructions for editing and annotating the information representation, respectively, by inversion of the stereoscopic presentation.
 21. A method implemented by a data processing system comprising using one or more devices of the data processing system to perform acts including: constructing a lens having a plurality of polygonal. surfaces according to a lens function; and generating a stereoscopic presentation of a region within an information representation of a digital image, the stereoscopic presentation including a stereoscopic distortion of the digital image in the region surrounded by undistorted portions of the digital image outside of the region by: creating first and second transformed presentations by overlaying first and second images of the information representation of the digital image onto the constructed lens for the region, the plurality of polygonal surfaces forming a single distorted surface upon which the first and second images are overlaid; and perspectively projecting the constructed lens having the overlaid first and second images onto a plane in first and second directions aligned with first and second viewpoints for the region, respectively, the constructed lens configured to adjust in accordance with one or more signals received by the data processing system from a graphical user interface (GUI) rendered over the region.
 22. A method as recited in claim 21 wherein the information representation is a stereoscopic image.
 23. A method as recited in claim 21 wherein the information representation is a monoscopic image.
 24. A method as recited in claim 21 wherein the information representation comprises a stereoscopic image that includes the first and second images.
 25. A method as recited in claim 21 wherein the plurality of polygonal surfaces form a single distorted surface upon which the first and second images are overlaid.
 26. One or more computer-readable memories storing instructions that, responsive to being executed by one or more devices of a data processing system, cause the one or more devices of the data processing system to perform operations comprising: constructing a lens having a plurality of polygonal surfaces according to a lens function; and generating a stereoscopic presentation of a region within an information representation of an image stored in memory of the data processing system, the stereoscopic presentation including a stereoscopic distortion of the image in the region surrounded by undistorted portions of the image outside of the region by: overlaying first and second images of the region within the information representation onto the constructed lens for the region, the overlaying including: producing the first and second images of the region; and texture mapping the first and second images to the plurality of polygonal surfaces of the constructed lens; and perspectively projecting the constructed lens having the overlaid first and second images onto a plane in first and second directions aligned with first and second viewpoints for the region, respectively, the constructed lens configured to adjust responsive to one or more signals from a (GUI) rendered over the region.
 27. One or more computer-readable memories as recited in claim 26 wherein the information representation is a monoscopic image.
 28. One or more computer-readable memories as recited in claim 26 wherein the constructed lens comprises a single distorted surface, the first and second images being overlaid onto the single distorted surface.
 29. One or more computer-readable memories as recited in claim 26, wherein: the first and second images used to generate the stereoscopic presentation are stereoscopically paired images that form the information representation; and the stereoscopic presentation is projected monoscopically using a single perspective viewing volume.
 30. One or more computer-readable memories as recited in claim 26 wherein: the first and second images used to generate the stereoscopic presentation are stereoscopically paired images that form the information representation; the first and second images are overlaid onto a single distorted surface corresponding to the plurality of polygonal surfaces; and the stereoscopic presentation is projected stereoscopically using two perspective viewing volumes. 